1. Field of the Invention
The present invention relates to an apparatus for a intermittent feeding of a strip shaped blank to a press equipped with tools for a intermittent working of the strip shaped blank, said feeding apparatus having a housing, a first feeding roller and a second feeding roller, which feeding rollers are adapted to accommodate the strip shaped blank arranged between same to be fed, and having a first intermittently operating electric servomotor which is drivingly connected to at least said first feeding roller, which first feeding roller includes a longitudinal axis and is designed symmetrically relative to a plane of symmetry extending perpendicularly to said longitudinal center axis; and having further a elongate rocker which includes a first and a second end which second end is located opposite said first end; which first feeding roller is supported for rotation in said rocker; which second feeding roller is arranged on a roller shaft and is rigidly connected thereto; which rocker is arranged at its first end on a first end area of a rocker shaft and is rigidly connected thereto; which rocker shaft is mounted for rotation at a second end area opposite the first end area in said housing, so that said rocker is supported in a overhung state; further having a means for a lifting off of a feeding roller, which means includes a control rod which is pivotally mounted to said second end of said rocker, which control rod includes a longitudinal center axis; further having a feeding roller pressing on device which includes a spiral spring which rests at one of its ends on said rocker; which spiral pressing spring includes a further longitudinal center axis.
The invention relates also to a method of operating the feeding apparatus as set forth above, said feeding apparatus having a housing and a threaded spindle housing arranged on said housing; having a adjusting motor with a threaded spindle and a control apparatus, a adjusting nut arranged on said threaded spindle and displaceable along same by a rotating of said threaded spindle; having further a eccenter disk driven by a electromotor, on which eccenter disk a connecting rod is supported which at its end remote from said eccenter disk includes a oblong hole extending at least approximately parallel to said threaded spindle; having further a double arm lever device supported on said adjusting nut, and a second double arm lever device supported on a shaft which is supported in said threaded spindle housing; which first double arm lever device has a first arm which engages said connecting rod and a second arm which is pivotally mounted to a fishplate, which in turn is pivotally mounted to a first arm of said double arm lever device, onto a second arm of which a connecting rod unit is pivotally mounted which in turn is pivotally mounted to said rocker; having further a pressure spring located between said rocker and said threaded spindle housing and is adapted to press said rocker with a upper roller shaft supported therein and with the first, upper feeding roller against said lower feeding roller shaft with the second, lower feeding roller; said feeding apparatus having a control device and cooperates with a press having a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a upper dead center position and a bottom dead center position; and having a press control device which cooperates with said control feeding apparatus; and in which the oblong hole of the connecting rod which is moveable between a upper dead center position and a bottom dead center position has a upper and a lower end; and in which the first arm of said double arm lever device engages said connecting rod through a bolt which extends through said oblong hole, wherein in order to insert a new strip shaped blank between said upper feeding roller and said lower feeding roller, the upper feeding roller is moved into a high lift position in order to set in this position a predetermined distance between the upper feeding roller and the lower feeding roller.
The invention relates further to a method of operating the feeding apparatus of the kind set forth above, said feeding apparatus having a housing and a threaded spindle housing arranged on said housing; having a adjusting motor with a threaded spindle and a control apparatus, a adjusting nut arranged on said threaded spindle and displaceable along same by a rotating of said threaded spindle; having further a eccenter disk driven by a electromotor on which eccenter disk a connecting rod is supported which at its end remote from said eccenter disk includes a oblong hole extending at least approximately parallel to said threaded spindle; having further a double arm lever device supported on said adjusting nut, and a second double arm lever device supported on a shaft which is supported in said threaded spindle housing; which first double arm lever device has a first arm which engages said connecting rod and a second arm which is pivotally mounted to a fishplate, which in turn is pivotally mounted to a first arm of said double arm lever device, onto a second arm of which a connecting rod unit is pivotally mounted to said rocker; having further a pressure spring located between said rocker and said threaded spindle housing and is adapted to press said rocker with a upper roller shaft supported therein and with its first, upper feeding roller supported therein against said lower roller shaft with the second, lower feeding roller; said feeding apparatus having a control device and cooperates with a press having a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a upper dead center position and a bottom dead center position; and having a press control device which cooperates with said control device of the feeding apparatus; and in which the oblong hole of the connecting rod which is moveable between a upper dead center position and a bottom dead center position has a upper and a lower end; and in which the first arm of said first double arm lever device engages said connecting rod through a bolt which extends through said oblong hole.
The invention relates also to method of operating the feeding apparatus as set forth above, said feeding apparatus having a housing and a threaded spindle housing arranged on said housing; having a adjusting motor with a threaded spindle and a control apparatus, a adjusting nut arranged on said threaded spindle and displaceable along same by a rotating of said threaded spindle; having further a eccenter disk driven by a electromotor, on which eccenter disk a connecting rod is supported which at its end remote from said eccenter disk includes a oblong hole extending at least approximately parallel to said threaded spindle; having further a double arm lever device supported on said adjusting nut, and a second double arm lever device supported on a shaft which is supported in said threaded spindle housing; which first double arm lever device has a first arm which engages said connecting rod and a second arm which is pivotally mounted to a fishplate, which in turn is pivotally mounted to a first arm of said double arm lever device, onto a second arm of which a connecting rod unit is pivotally mounted to said rocker; having further a pressure spring located between said rocker and said threaded spindle housing and is adapted to press said rocker with a upper roller shaft supported therein and with the first, upper feeding roller supported therein against said lower roller shaft with the second, lower feeding roller; said feeding apparatus having a control device and cooperates with a press having a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a upper dead center position and a bottom dead center position; and having a press control device which cooperates with said control device of the feeding apparatus; and in which the oblong hole of the connecting rod which is moveable between a upper dead center position and a bottom dead center position has a upper and a lower end; and in which the first arm of said first double arm lever device engages said connecting rod through a bolt which extends through said oblong hole, which punch is driven by a rotating drive and the eccenter disk of the connecting rod is driven by a electromotor; which upper tool includes positioning pins adapted to precisely position said strip shaped blank in the press during any working procedure step performed on the strip; which positioning pins are moved into prepunched holes in said strip shaped blank, and which positioning pins include conical head portions, and said first, upper feeding roller is moved away from said second, lower feeding roller into a intermediate lifted position as soon as said conical head portions have been moved partly into the positioning holes, and thereafter moved again back to again rest on the strip shaped blank as soon as the conical head portions have been lifted partly out of the positioning holes.
2. Description of the Prior Art
The presses which herein are referred to are specifically high speed punch presses with a number of strokes up to 2000 strokes per minute. These presses are equipped with tools for a working or processing resp. of a (or several) strip shaped blank(s) fed to the press, whereby punching operations, embossing operations, bending operations, a riveting, a producing of threads are performed.
The movement of the strip shaped blank which is worked upon in the press proceeds, thereby, intermittently, i.e. step-wise. During a given working step, e.g. a punching, quite obviously no feeding movement of the strip-shaped blank occurs. It is often precisely positioned, that is arrested by positioning pins arranged in the tools. After the termination of such a given working step, for instance after a punching tool has been moved out of the punched hole, the strip-shaped blank is advanced, i.e. fed by a predetermined distance and again stopped, so that the next following working step can be performed.
The feeding or forwarding, resp. movement of the strip shaped blank proceeds by a (or several, located at the entry and of the exit of the press) feeding or forwarding, resp. apparatus(es) in order to draw the strip shaped blank intermittently off a storage roll and to feed it intermittently to the press.
The feeding apparatuses include typically feeding members in order to advance the strip shaped blank. It is, thereby, clamped and advanced by these feeding members. When the feeding members return again into their initial position, the clamping state is released. Additionally, the clamping is released for a short time during the time span within which the tools perform a working step on the strip shaped blank, specifically in the case of positioning pins.
The design of these feeding devices must meet basically 3 main functions, namely the high lifting (strip is being inserted), the setting based on the thickness of the strip (the upper feeding roller rests on the strip, play in the oblong hole of the connecting rod), and intermediate lifting (giving the strip free prior to each working step).
Designs of such feeding devices have become known in which the clamping members are designed as linearly moving clamping tongues. Other designs include oscillating segment rollers which perform rotary movements.
Furthermore, feeding apparatuses with electrical servomotors have become known. Thereby, a first servomotor is allocated to the feeding drive of the clamping members and a further, second servomotor is allocated to the intermittent lifting of a clamping member off the strip shaped blank. Such servomotors are made and sold by several companies. The operation of these servomotors is electronically controlled. These new feeding devices comprise as feeding members completely cylinder shaped feeding rollers arranged on shafts which rotate intermittently always in the same sense of rotation. Of these feeding rollers one is supported in a structure which is drivingly connected to a further servomotor, and due to the operation of this structure this feeding roller is moved towards the strip shaped blank for a clamping of same and away from the strip shaped blank in order to release same.
Due to the present high number of strokes, the masses of the moving parts of a feeding apparatus play a large role due to their forces of inertia and their moments of inertia, and have, furthermore, a large influence regarding the precision of the fabricated product. Furthermore, the arrangement and the design of these moving parts must be, due to the time spans for the acceleration and deceleration of movements, such that a operation with a high number of strokes can be performed safely.
Furthermore, it is possible that torsional moments due to influences of forces are generated in individual structural members which can lead to a slanted position of the feeding roller, so that further negative influences leading to a decrease of the precision of the finished product are produced.